Hyoscyamine, one of the principal alkaloid components of belladonna, is a potent anticholinergic agent. Because of its anticholinergic properties, hyoscyamine sulfate drops are often prescribed for the treatment of colic in infants. Anticholinergic poisoning in infants is rare. However, five cases are reported of infants with anticholinergic toxicity following the administration of hyoscyamine drops for the treatment of colic. Common presenting symptoms included irritability, tachycardia, and erythematous flushed skin. These cases emphasize the need for a heightened awareness by emergency physicians and pediatricians of possible anticholinergic toxicity caused by the use of hyoscyamine for infant colic.